12
DOK41 HOIAO WxDEN · FD 9912
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English
Air-to-water heat pump 4 - 6 kW
Guideline values for filling and make-up water in accordance with
VDI 2035
For systems with an above-average specific system volume of
50 l/kW, VDI 2035 recommends the use of fully demineralised
water and a pH stabiliser to minimise the risk of corrosion in the
heat pump and heating system.
!!
ATTENTION!
With fully demineralised water, it is important to ensure that
the minimum pH value of 7.5 (minimum permissible value for
copper) is complied with. Failure to comply with this value can
result in the heat pump being destroyed.
Minimum heating water flow rate
The minimum heating water flow rate of the heat pump is guar-
anteed by the installed overflow valve. The procedure for set-
ting an overflow valve is described in the chapter „Commission-
ing“. When the minimum heating water flow rate is undershot,
the plate heat exchanger in the refrigeration circuit can freeze,
which can lead to total loss of the heat pump.
The nominal flow rate is specified depending on the max. flow
temperature in the device information and must be taken into
account during planning. With design temperatures below
30 °C in the flow, the design must be based on the max. volume
flow with 5 K spread for A7/W35.
The specified nominal flow rate (see “Device information”) must
be assured in all operating statuses. The installed flow rate
monitoring is used only for switching off the heat pump in the
event of an unusual and abrupt drop in the heating water flow
rate and not to monitor and safeguard the nominal flow rate.
Frost protection
A method of manual drainage should be provided for heat
pumps which are exposed to frost. The frost protection func-
tion of the heat pump manager is active whenever the heat
pump manager and the heat circulating pump are ready for op-
eration. The system must be drained if the heat pump is taken
out of service or in the event of a power failure. The heating cir-
cuit should be operated with a suitable frost protection if heat
pump systems are implemented in buildings where a power
failure can not be detected (holiday home).
6.4 Domestic hot water connection
Installation and commissioning must be performed by an au-
thorised specialist company. The entire system, including all
factory-assembled components, should be inspected to ensure
that everything is working properly and that there is no leakage.
The enamelled tank in accordance with DIN 4753 is suitable for
drinking water.
The following materials can be used in the consumer circuit in
the domestic hot water circuit:
Copper
Stainless steel
Brass
Plastic
Depending on the materials used in the domestic hot water
system (customer installation), material incompatibility may
lead to corrosion damage. This especially applies to zinc-plated
materials and materials containing aluminium. If there is a risk
of water contamination during operation, install a suitable filter.
The maximum permissible operating overpressure indicated on
the type plate must not be exceeded. It may be necessary to
mount a pressure reducer.
Ensure that the water supply is turned on and the cylinder is
filled before start-up.
The domestic hot water cylinder must be equipped with a certi-
fied, spring-loaded membrane safety valve on-site. A shut-off
device must not be installed between the cylinder and the
safety valve. The operational reliability of the valve must be
checked at regular intervals. We recommend having an annual
service inspection carried out by a qualified specialist company.
Total heat
output in
kW
Total
Alkaline earths
in mol/m³ and/
or mmol
Specific system volume
(VDI 2035) in l/kW
< 20
20 < 50
50
Total hardness in °dH
< 50
2.0
16.8
11.2
< 0.11
50 - 200
2.0
11.2
8.4
200 - 600
1.5
8.4
< 0.11
> 600
< 0.02
< 0.11
1
1. This value lies outside the permissible value for heat exchangers
in heat pumps.